Metabolic landscape of the mouse liver by quantitative 31 P-NMR analysis of the phosphorome.

The liver plays a central role in all metabolic processes in the body. However, precise characterization of liver metabolism is often obscured by its inherent complexity. Phosphorylated metabolites occupy a prominent position in all anabolic and catabolic pathways. Here we develop a 31 P-NMR-based method to study the liver "phosphorome" through the simultaneous identification and quantification of multiple hydrophilic and hydrophobic phosphorylated metabolites. We applied this technique to define the metabolic landscape in livers form a mouse model of the rare disease disorder congenital erythropoietic porphyria (CEP), as well as two well-known murine models of nonalcoholic steatohepatitis, one genetic, methionine adenosyltransferase 1A knockout mice, and the other dietary, mice fed a high-fat choline deficient diet. We report alterations in the concentrations of phosphorylated metabolites that are readouts of the balance between glycolysis, gluconeogenesis, the pentose phosphate pathway, the tricarboxylic acid cycle and oxidative phosphorylation, and of phospholipid metabolism and apoptosis. Moreover, these changes correlate with the main histological features: steatosis, apoptosis, iron deposits and fibrosis. Strikingly, treatment with the repurposed drug ciclopirox improves the phosphoromic profile of CEP mice, an effect that was mirrored by the normalization of liver histology. In conclusion, these findings indicate that NMR-based phosphoromics may be used to unravel metabolic phenotypes of liver injury and to identify the mechanism of drug action.